It's not like after the date you can no longer play games.
You just won't get performance improvements for games that the GPU can't even run very well. At least not without turning it down to 1080p Medium or lower
It will eventually mean just that for some games.
Not that it is such a bad thing. Most of the cards are 8 years old and are long past the expected lifetime of the caps.
Kepler is a one thing at a time arch. Try to throw async compute, or any concurrent compute at it and it's performance suffers.
Ampere can totally handle async and can do RT and tensor loads as well.
A lot of this may be a message to devs to finally give up on restricting their games to accommodate for an arch that holds them back feature wise.
My 780ti is still a competent 1080p card with old fashioned rasterized games including CP2077 and walks all over the 1050ti in my laptop. It holds up to the Techpowerup 1080p rating on the specs page just fine in games like that. But new games shouldn't be restricted to having compatibility with a relative relic.
My 580 still plays a lot of new games slowly, but some are incompatible, like SOTTR where not all of the triangles fill every frame and flicker black. Many new ones just don't start. Some of this may also be the 1.5GB vram. Either way games have gotten better moving on from Fermi and they will continue getting better moving on from Kepler.